Reinforced fusible element

ABSTRACT

A reinforced fusible element useful in fire extinguishing sprinklers, fusible links on fire doors and the like is disclosed wherein the fusible material usually solder of a lead alloy or the like is provided with a thin frangible covering for stabilizing its size and shape by acting to prevent cold flow of the alloy as a result of compressive or tension forces thereagainst. Specifically a fusible element may be provided with a thin plated metal coating restricting growth due to cold flow in any direction.

Unite @tates ?atent Audi [ 1 Feb.1,1972

[541 REINFORCED FUSIBLE ELEMENT [72] Inventor: Wayne E. Anlt, Aurora,Ohio [73] Assignee: A-T-O 1nc., Willoughby, Ohio [22] Filed: Sept. 23,1970 [21] App1.No.: 74,810

Related US. Application Data [63] Continuation-impart of Ser. No.806,123, Mar. 11,

[51] Int. Cl ..A62c 37/30 [58] Field ofSeareh ..169/38, 39,40, 42;29/180, 29/191.4, 191.2, 183.5; 161/170; 122/5043; 222/54 [56]References Cited STATE S PATENTS 1,362,236 1 2/ 19 20 Delaney ....leg/3gJuras ..29/180 R Macanney 169/38 Primary ExaminerM. Henson Wood, .Ir.Assistant ExaminerMichael Y. Mar AttameyWebster B. Harpman [5 7]ABSTRACT A reinforced fusible element useful in fire extinguishingsprinklers, fusible links on fire doors and the like is disclosedwherein the fusible material usually solderof a lead alloy or the likeis provided with a thin frangible covering for stabilizing its size andshape by acting to prevent cold flow of the alloy as a result ofcompressive or tension forces thereagainst. Specifically a fusibleelement may be provided with a thin plated metal coating restrictinggrowth due to cold flow in any direction.

6 Claims, 5 Dr yving Figures PATENTED FEB 1 I972 m m E v m Wa yne E. Au/f ATTORNEY.

REINFORCED FUSIBLE ELEMENT This is a continuation-in-part ofapplication, Ser. No. 806,123 filed Mar. 11, 1969.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to fusible elements of the type normally employed to hold otherdevices in predetermined relation pending attainment of a predeterminedtemperature upon which the other devices are to be released by fusing,that is softening of the fusible element.

2. Description of the Prior Art Prior fusible elements have generallyconsisted of appropriately shaped units of a desirable fusible alloy,the fusing or softening temperature of which may be readilypredetermined. Such elements are generally in compression in a deviceusing the same such as a fire extinguishing sprinkler head wherein thelevers holding a cap on a discharge orifice are in turn held in desiredposition by the physical presence of the fusible element and so arrangedthat alteration in shape of the fusible element permits the levers tomove to a position opening the cap on the discharge orifice. Somefusible elements have been positioned in retaining members as forexample in U.S. Pat. Nos. 1,362,236; 2,004,833; and 2,502,754.

The present invention ensures the retention of the desired physicalshape of the fusible element and precludes accidental operation due tocold flow of the fusible element or other alterations in its shape dueto causes other than those responsive to temperature at a desireddegree.

SUMMARY OF THE INVENTION A fusible element comprises a pelletlikeportion of a metallic alloy such as for example an alloy which will fuseat 165 F. and consists of 30.51 percent lead, 24.45 percent tin 41.22percent bismuth and 3.82 percent cadmium.

Those skilled in the art will recognize that the percentages of thematerials will vary depending upon the temperature at which the fusibleelement is to become operable.

The ability of fusible alloys such as the above example to withstandcompression without cold flow of the alloy is limited and the presentinvention provides means for ensuring against such cold flow and therebymaintaining the physical shape of the fusible alloy as desired until thefusing temperature is reached. This is made possible by the use of athin frangible covering restraining the radial growth of a fusibleelement and/or the addition of fibers of bondable material throughoutthe fusible element and/or the jacketing of the fusible element in awoven flexible nonstretchable sleeve.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation of a fireextinguishing sprinkler showing a fusible element holding the mechanicallevers thereof fixed orifice closing position.

FIG. 2 is a greatly enlarged side elevation of a fusible element havinga thin frangible covering thereabout, with parts broken away and partsin cross section.

FIG. 3 is an end view of the fusible element and covering of FIG. 2,with parts broken away and parts in cross section.

FIG. 4 is a cross section on a greatly enlarged scale of a fusibleelement incorporating suitable fibers disposed throughout and bonded tothe alloy of the fusible element.

FIG. 5 is a perspective view on a greatly enlarged scale showing afusible element having a loosely woven flexible but nonstretchablejacket thereabout.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 of the drawing atypical environmental use of a fusible element may be seen to compriseafire extinguishing sprinkler which device includes a frame a threadedbase 11 defining a passageway normally closed by a cap 12. A deflector13 is affixed to the frame 10 in oppositely disposed relation to the cap12 as will be understood by those skilled in the art.

A compression pin 14 positioned centrally through the upper portion 15of the frame 10 engages a plurality of levers 16, 17 and 18 respectivelywith the levers 18 being held in spacedapart relation by a fusibleelement 19.

The exterior configuration of the oppositely disposed spaced-apartlevers 18 is such that they cannot move through an opening 20 in thelever 16 until the fusible element 19 fuses so as to change shape andpermit the levers 18 to move toward one another sufficiently that theirconfigurations will clear the opening 20 whereupon the levers 16, 17 and18 fall free and permit the cap 12 to open the discharge orifice in thesprinkler.

In the prior art constructions the fusible element 19 is simply formedof a metal alloy that would fuse at a desired predetermined temperature.For example, these are conventionally 212, 286 and 360 F. In practicalexperience it has been found that when compression is constantlymaintained on a fusible element it tends to alter its shape by reason ofcold flow of material and sometimes to the point where accidentaloperation of the device controlled thereby results.

In order to utilize an inexpensive easily assembled mechanical leverarrangement in a fire extinguishing sprinkler such as that shown in FIG.1 of the drawings, it is necessary to place the fusible element undersome degree of compression. By utilizing the invention disclosed hereinthe modified fusible element becomes capable of withstanding thecompressive forces applied thereto without altering its shape and yet befully responsive in operation to a fusing temperature.

In FIG. 2 of the drawings a fusible element 21 of solid cylindricalshape is shown in side elevation with thin frangible covering 22positioned thereabout. The main body of fusible element 21 is formed ofa fusible alloy such as that hereinbefore described and the thinfrangible covering 22 may be formed of an electroplated metal such aschrome, nickel, brass or the like which is of a thickness for example0.0003 inch, the thickness of the covering 22 being only sufficient torestrain any tendency of the body of the fusible element 21 to enlargeradially, and thin enough to be unable to resist collapse of theassembly of the element 21 and covering 22.

In FIG. 3 of the drawings an end view of the fusible element 21 may beseen and it will be observed that the covering 22 extends completelythereabout. It will be seen that the covering 22 is of a very fragilenature, sufficient only to hold the fusible body 21 in place and inhibitcreep and/or cold flow, and that in itself will support no load incompression and will collapse on fusing of the element 21. The coveringmay be formed of a suitable synthetic resin such as polystyrene arrangedto incorporate the desirable characteristics hereinabove set forth.

In FIG. 4 of the drawings a fusible element 23 is illustrated which is asolid cylindrical shape of fusible alloy as hereinbefore described andincorporating a plurality of random length fibers 24 distributedthroughout. The fibers may be natural fibers, synthetic resin fibers,metallic fibers such as fine metal wire or metal shavings such as steelwool and the like and bondable to the fusible alloy so as to become anintegral part thereof. The reinforcing action of the many fibers withinthe body of the fusible element 22 reinforces the same and prevents itsgrowth longitudinally or radially except at fusing temperatures of thealloy.

FIG. 5 of the drawings a perspective view of a fusible element 25 may beseen and it is enclosed on its outer circular surface with a looselywoven jacket 26 of diagonally positioned woven fibers 27 so as to form aflexible but nonstretchable jacket thereabout. A preferred embodiment ofthe form of the invention illustrated in FIG. 5 would comprise a looselywoven wire braid such as for example that used in hydraulic hoseconstructions and bondable to the surface of the fusible element so asto prevent relative movement therebetween while being capable ofcollapse upon fusing of said element.

It will thus be seen that a fusible element has been disclosed inseveral forms which is arranged to prevent changes in its physical shapeat temperatures less than the fusing temperature of the alloy of whichthe fusible element is formed. The thin frangible covering of FIGS. 2and 3, the fibers of FIG. 4 and the woven jacket of F l6. 5 all preventundesirable change of shape of the fusible element and thereby meet theprincipal object of the invention.

Although but three embodiments of the present invention have beenillustrated and described it will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the spirit of the invention.

I claim:

1. A fusible element comprising a shaped section of a fusible alloyhaving a thin covering means, said means consisting of a coveringmaterial of a thickness to restrain creep and cold flow of said alloy attemperatures less than the fusing temperature of said alloy and beingcollapsible upon fusing of said alloy.

2. The fusible element set forth in claim 1 and wherein the coveringmeans restraining cold flow of the alloy comprises a coating ofnonstretchable material positioned thereabout.

3. The fusible element set forth in claim 1 and wherein the coveringmeans restraining cold flow of the alloy of the fusible elementcomprises an electroplated metallic coating.

4. The fusible element set forth in claim 1 and wherein the meansrestraining the cold flow of the alloy of the fusible element comprisesa nonstretchable woven jacket enclosing said fusible element, andcapable of collapse upon fusing of said element.

5. The fusible element set forth in claim 1 and wherein a plurality offibers are distributed throughout said fusible alloy and bonded thereto.

6. The fusible element set forth in claim 1 and wherein the coveringmeans restraining cold flow of the alloy of the fusible elementcomprises a synthetic resin coating.

1. A fusible element comprising a shaped section of a fusible alloyhaving a thin covering means, said means consisting of a coveringmaterial of a thickness to restrain creep and cold flow of said alloy attemperatures less than the fusing temperature of said alloy and beingcollapsible upon fusing of said alloy.
 2. The fusible element set forthin claim 1 and wherein the covering means restraining cold flow of thealloy comprises a coating of nonstretchable material positionedthereabout.
 3. The fusible element set forth in claim 1 and wherein thecovering means restraining cold flow of the alloy of the fusible elementcomprises an electroplated metallic coating.
 4. The fusible element setforth in claim 1 and wherein the means restraining the cold flow of thealloy of the fusible element comprises a nonstretchable woven jacketenclosing said fusible element, and capable of collapse upon fusing ofsaid element.
 5. The fusible element set forth in claim 1 and wherein aplurality of fibers are distributed throughout said fusible alloy andbonded thereto.
 6. The fusible element set forth in claim 1 and whereinthe covering means restraining cold flow of the alloy of the fusibleelement comprises a synthetic resin coating.